code: def matching_dict_to_set(matching):
      """Converts matching dict format to matching set format
  
      Converts a dictionary representing a matching (as returned by
      :func:`max_weight_matching`) to a set representing a matching (as
      returned by :func:`maximal_matching`).
  
      In the definition of maximal matching adopted by NetworkX,
      self-loops are not allowed, so the provided dictionary is expected
      to never have any mapping from a key to itself. However, the
      dictionary is expected to have mirrored key/value pairs, for
      example, key ``u`` with value ``v`` and key ``v`` with value ``u``.
  
      """
      edges = set()
      for edge in matching.items():
          u, v = edge
          if (v, u) in edges or edge in edges:
              continue
          if u == v:
              raise nx.NetworkXError(
                  f"Selfloops cannot appear in matchings {edge}"
              )
          edges.add(edge)
      return edges
  
file_path: networkx/networkx/algorithms/matching.py
imports: from collections import Counter
  from itertools import combinations, repeat
  import networkx
  from networkx.utils import not_implemented_for
label_desc: Use image node_id 2 for calling a global function with example usage: matching_dict_to_set(matching) and returns: edges